You're right it is pointless looking for reasons, but it's also very natural so forgive yourself the odd lapse.
Honestly you sound as you're doing pretty well only 4 months in. I was still weeping on the floor at that stage !! The people on here were amazing, and although you don't wish misery on someone else it's a real help to hear how many others have been through this horrible process and not only survived but thrived too. I'm 2.5 yrs down the line and my life is not perfect, but I'm happy now in a way I wouldn't have thought possible at the time.
I think one of the best pieces of advice I was given here was when I posted something like 'why does this still hurt so much ?' And the reply was because I allowed it too. It takes time but you do eventually realise only you are now responsible for how you feel, and you start to take control again. Learn to appreciate you and look after yourself again. Be brave, get yourself out of your comfort zone and hopefully make new friends. It's so hard when your life has been shaken so badly but only you can make the difference.
Loneliness is a killer to start with (especially in the evenings) but again I think you learn to find the positives. I'll never have to watch hours of motorsports again !! It's tough to quieten the whirring in your head at night, I still don't sleep brilliantly, but someone on here suggested listening to podcasts with headphones while you try to fall asleep and that really helped me.
You are doing great, but they don't call this a rollercoaster for nothing.